de.lmu.ifi.dbs.elki.algorithm.clustering.em

Class SphericalGaussianModel

java.lang.Object

de.lmu.ifi.dbs.elki.algorithm.clustering.em.SphericalGaussianModel

All Implemented Interfaces:

EMClusterModel<EMModel>

public class SphericalGaussianModel
extends java.lang.Object
implements EMClusterModel<EMModel>

Simple spherical Gaussian cluster.

Since:

0.7.0

Author:

Erich Schubert

Field Summary

Fields

Modifier and Type	Field and Description
(package private) double	logNorm Normalization factor.
(package private) double	logNormDet Normalization factor.
(package private) double[]	mean Mean vector.
(package private) double[]	nmea Temporary storage, to avoid reallocations.
(package private) double	priorvar Prior variance, for MAP estimation.
(package private) double	variance Variances.
(package private) double	weight Weight aggregation sum.
(package private) double	wsum Weight aggregation sum.

Constructor Summary

Constructors

Constructor and Description
SphericalGaussianModel(double weight, double[] mean) Constructor.
SphericalGaussianModel(double weight, double[] mean, double var) Constructor.

Method Summary

Modifier and Type	Method and Description
void	beginEStep() Begin the E step.
double	estimateLogDensity(NumberVector vec) Estimate the log likelihood of a vector.
EMModel	finalizeCluster() Finalize a cluster model.
void	finalizeEStep(double weight, double prior) Finalize the E step.
double	getWeight() Get the cluster weight.
double	mahalanobisDistance(double[] vec) Compute the Mahalanobis distance from the centroid for a given vector.
double	mahalanobisDistance(NumberVector vec) Compute the Mahalanobis distance from the centroid for a given vector.
void	setWeight(double weight) Set the cluster weight.
void	updateE(NumberVector vec, double wei) Process one data point in the E step

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface de.lmu.ifi.dbs.elki.algorithm.clustering.em.EMClusterModel

finalizeFirstPassE, firstPassE, needsTwoPass

Field Detail

mean

double[] mean

Mean vector.

variance

double variance

Variances.

nmea

double[] nmea

Temporary storage, to avoid reallocations.

logNorm

double logNorm

Normalization factor.

logNormDet

double logNormDet

Normalization factor.

weight

double weight

Weight aggregation sum.

wsum

double wsum

Weight aggregation sum.

priorvar

double priorvar

Prior variance, for MAP estimation.

Constructor Detail

SphericalGaussianModel

public SphericalGaussianModel(double weight,
                              double[] mean)

Constructor.

Parameters:

weight - Cluster weight

mean - Initial mean

SphericalGaussianModel

public SphericalGaussianModel(double weight,
                              double[] mean,
                              double var)

Constructor.

Parameters:

weight - Cluster weight

mean - Initial mean

var - Initial variance

Method Detail

beginEStep

public void beginEStep()

Description copied from interface: EMClusterModel

Begin the E step.

Specified by:

beginEStep in interface EMClusterModel<EMModel>

updateE

public void updateE(NumberVector vec,
                    double wei)

Description copied from interface: EMClusterModel

Process one data point in the E step

Specified by:

updateE in interface EMClusterModel<EMModel>

Parameters:

vec - Vector to process

wei - Weight of point ("responsibility" of the cluster)

finalizeEStep

public void finalizeEStep(double weight,
                          double prior)

Description copied from interface: EMClusterModel

Finalize the E step.

Specified by:

finalizeEStep in interface EMClusterModel<EMModel>

Parameters:

weight - weight of the cluster

prior - MAP prior (0 for MLE)

mahalanobisDistance

public double mahalanobisDistance(double[] vec)

Compute the Mahalanobis distance from the centroid for a given vector.

Parameters:

vec - Vector

Returns:

Mahalanobis distance

mahalanobisDistance

public double mahalanobisDistance(NumberVector vec)

Compute the Mahalanobis distance from the centroid for a given vector.

Parameters:

vec - Vector

Returns:

Mahalanobis distance

estimateLogDensity

public double estimateLogDensity(NumberVector vec)

Description copied from interface: EMClusterModel

Estimate the log likelihood of a vector.

Specified by:

estimateLogDensity in interface EMClusterModel<EMModel>

Parameters:

vec - Vector

Returns:

log likelihood.

getWeight

public double getWeight()

Description copied from interface: EMClusterModel

Get the cluster weight.

Specified by:

getWeight in interface EMClusterModel<EMModel>

Returns:

Cluster weight

setWeight

public void setWeight(double weight)

Description copied from interface: EMClusterModel

Set the cluster weight.

Specified by:

setWeight in interface EMClusterModel<EMModel>

Parameters:

weight - Cluster weight

finalizeCluster

public EMModel finalizeCluster()

Description copied from interface: EMClusterModel

Finalize a cluster model.

Specified by:

finalizeCluster in interface EMClusterModel<EMModel>

Returns:

Cluster model